Magnetostrictively actuated control flaps for vibration reduction in helicopter rotors—design considerations for implementation

Recently, there has been substantial research on the development of a hybrid hydraulic pump driven by various smart materials. Piezo-hydraulic actuators have already been developed for potential use in smart rotor applications. However, at high actuation frequencies, piezo-stacks generate significant heat mainly due to the hysteresis losses that can deteriorate their performance and permanently damage the piezo material. In contrast, magnetostrictive materials are more robust than piezostacks, especially at high temperatures, while offering almost the same bandwidth and higher maximum induced strain when compared with piezoelectric stacks. Also, the magnetostrictive material usually has a particular frequency range where the hysteretic losses taking place are minimum and consequently the operation results in least heat generation. As a result, to operate the pump with higher flow rate with minimum heat generation and maximum efficiency, we need to know the system resonance. Moreover, the hybrid pump with smart material is mechanically more complex than a single rod actuator; consequently, it can have more than one resonant frequency depending on the number of degrees of freedom of the system. A hybrid pump using the magnetostrictive material Terfenol-D has been developed in our laboratory with hydraulic oil as the working fluid. Several key design parameters, which include output cylinder size, diaphragm thickness, reed valve thickness and tubing diameter, along with operational conditions, like input current and bias pressure within the fluid, have been varied to identify a set of optimum driving conditions. Tests at no-load have been carried out for unidirectional motion of the output piston. In this paper, we develop a dynamic model of the hydraulic hybrid actuator to show the basic operational principle and compare the simulated data with test results. The final target of this study is to find optimal operational frequency to get highest performance and also to predict the pump sizing for a desired output velocity and load lifting capability.

One and two dimensional sensory mechanisms, corresponding to one patch and a line array, respectively, of sensory cells are analyzed. A fundamental stimulus conversion law to average neural pulse rate is employed to explain several phenomena in psychophysics. A theory for neural noise is developed which is shown to specify the limits to animal discrimination and to explain certain observed neural mechanisms. Finally, concepts of optimum detection are employed to specify the ideal animal recognition sensory schema as limited by constraints associated with unavoidable neural noise. Actual animal mechanisms appear to follow the ideal. Certain aspects of Gestalt psychology are also evidenced. The general theory provides quantitative insight into artificial animal recognition and information handling systems and indicates the extent to which the capability of a mechanical device can equal or exceed that of its living counterpart. Explicit design considerations for implementation of the ideal artificial animal system are provided.

In this paper, the best actuation schedules exploiting various waveform types are sought taking advantage of the global search algorithm for the reduction of the power required and/or hub vibration of a rotor in high speed forward flight. The active twist schedules include two non-harmonic inputs formed based on segmented step functions along with the simple harmonic waveform input. An advanced particle swarm assisted genetic algorithm (PSGA) is employed for the optimizer. A rotorcraft computational structural dynamics (CSD) code CAMRAD II is used to perform the rotor aeromechanics analysis. A CFD/CSD coupling is introduced to assist the observations made using the CSD analysis. The PSGA optimization results are verified against the parameter sweep study performed by the harmonic actuation. The best optimum twist schedules according to the performance or vibration reduction strategy are identified and their optimization gains are compared between the actuation cases. A two-phase non-harmonic actuation schedule demonstrates the best outcome in decreasing the rotor power required while a four-phase non-harmonic schedule leads to the best vibration reduction. The mechanism of reduction gains is identified illustrating the section airloads, angle-of-attack distribution, and net elastic twist deformation predicted using CSD and CFD/CSD approaches.

Aircraft maintenance is one of the most important cost items faced by the operators of air fleets and is a major contributor to the aircraft life cycle cost. An aircraft fly-by-wire flight control system has a total of primary flight control actuators ranging from 10 to 20 depending on the aircraft type, with a failure rate of 1/1000 flight-hours; therefore, a health monitoring system for primary flight control actuators, able to recognize an actuator degradation in its early stage could greatly contribute to optimize the maintenance operations, reduce the airplane downtime and prevent missions interruptions.This note presents the initial part of an ongoing research project aimed at developing a prognostic and health management system for fly-by-wire primary flight control actuators. A key feature of the project is to develop a PHM system for these actuators suitable for the flight control actuators of legacy airplanes, which are poised to operate for still a long time, and not only for those of new aircraft. The primary flight control actuators of fly-by-wire flight control systems of existing aircraft are electrohydraulic servoactuators with a typical configuration and complement of transducers, and there is no practical possibility of introducing additional sensors. For this reason, the research activity was directed towards the study of algorithms able to identify faults only by using the already available information of the servoactuators state variables.The implemented algorithms are a combination of mathematical and neural network based ones, and the identification of degradations was performed by the analysis of the response of the servoactuators to a sequence of selected stimuli provided in preflight or postflight. The servovalve current and the feedback position are processed by dedicated algorithms in order to obtain significant indicators of the servocatuator health condition. The values of the indicators obtained during the sequence of stimuli are analyzed in combination with those obtained in the past.This is performed by the neural network part of the algorithm which allows a reliable identification of presence and of type of a degradation.The results obtained from the initial part of the research activity are interesting and encouraging. Individual degradations of the servoactuator parameters have so far been addressed and the algorithms for identifying them have been developed. All that makes up the foundations of the future research activity which will be focused on analyzing the effects of simultaneous multiple degradations and to the estimation of the remaining useful life.

Helicopter dronization is expanding, as for example with the VSR700 project, and leads to the design and the integration of electromechanical actuators (EMA) into the primary flight control system (PFCS). The PFCS is in charge of controlling the helicopter flight over its 4 axis (roll, pitch, yaw, vertical). It controls the blade pitch through dedicated mechanical kinematics and actuators. The hydraulic technology has been conventionally used in actuators for more than 60 years. On the other hand, the introduction of the EMA technology requires the reconsideration of design practices right at development start. Indeed, the establishment and synthesis of the specification need to deal with – new design drivers (high performance points, wear, fatigue) and - new inherent technological imperfections (friction, inertia and reduction ratio). To address these topics, this paper draws a list of the main EMA design drivers to focus on along with a brief description of the main EMA components. Then, it proposes indicators evaluated over a complete mission profile in time coming from measurement on a given applicative helicopter flight. These indicators are chosen and elaborated to provide an image of the design drivers responsible for rapid and gradual degradations of the actuator components. Also, they give an idea of the importance taken by the actuator imperfections into the global performance. Furthermore, we explain how mission profiles are processed depending of data sources. Finally, through a comparison with a standard aircraft mission profile, we emphasize the specificity of the helicopter application use case.

In this paper, an analytical model of a new bulk magnetostrictive actuator in three modes-longitudinal, bending, and torsional-are examined. The magnetostrictive material considered is a cylindrical vanadium permendur. This actuator is capable of operating in the mentioned modes both independently and in combination. Three constant magnetic fields are used to actuate the device in axial, bending, and torsional modes, and the calculation of each magnetostrictive coefficient dij​ is performed by considering all magnetic fields. The longitudinal deformation is applied through the Joule effect by stimulating the magnetostrictive material with a coaxial coil surrounding the material. The torsional mode is implemented via the Wiedeman effect by passing an electric current through a wire inside the magnetostrictive material. For the bending mode, the stimulation is achieved by applying a magnetic field on a surface of the material using a magnetic coupler. The actuator modeling is conducted using classical magnetostrictive equations, and the magnetostriction coefficients are modified for the excitation magnetic fields. Experimental tests are conducted to measure the coefficients. Ultimately, the magnetostrictive deformations in three modes are precisely refined and presented using nonlinear regression relationships.

This paper discusses the design considerations of switched reluctance machines (SRMs) for structural vibration reduction. The characteristics of vibration in SRMs at both non-resonant and resonant conditions are presented. Significant design variables for vibration reduction without sacrificing torque output are identified by performing a sensitivity analysis based on Design of Experiments (DoEs). A comprehensive study on the identified significant design variables is conducted to assess the effects of each of these variables on machine vibration. The design considerations for vibration reduction of SRMs are provided from both electromagnetic and mechanical perspectives. This work is carried out based on finite element analysis simulation results.

The system is investigated, in which micrometric displacements are obtained by mechanical means and nanometric displacements - by variation of magnetic flux directed through magnetostrictive material terfenol-D. The permanent magnet is used as a magnetic flux source. A parallel branch to terfenol-D rod’s magnetic circuit branch enables to form nanometric and micrometric displacements separately and independently. Nanometric displacements are formed by variation of the air gap at the parallel branch. It is recommended to shield the air gap by ferromagnetic screen. In this case the dependence of magnetic flux through the terfenol-D rod versus the air gap is practically linear. Ill. 8, bibl. 2 (in English; summaries in English, Russian and Lithuanian).

In this study, authors presented the feasibility study of the magnetostrictive vibration energy harvester under the low intensity excitation condition, 0.71[mm/s] (RMS). The experimentally obtained power generation performance of the vibration energy harvester was quite low comparing with the previous authors' studies about the piezocomposite vibration energy harvester.

Individuals with multiple chronic conditions (MCCs) and mental health challenges such as depression or anxiety have complex health needs and experience significant challenges with care coordination. Approaches to enhance care for patients with MCCs typically focus on eliciting patients' values to identify and align treatment priorities across patients and providers. However, these efforts are often hindered by both systems- and patient-level barriers, which are exacerbated for patients with co-occurring mental health symptoms. Technology-enabled services (TES) offer a promising avenue to facilitate values elicitation and promote patient-centered care for these patients, though TES have not yet been tailored to their unique needs. This study aimed to identify design and implementation considerations for TES that facilitate values elicitation among patients with MCCs and depression or anxiety. We sought to understand the preferences of both clinicians and patients for TES that could bridge the gap between mental and physical health care. Using human-centered design methods, we conducted 7 co-design workshops with 18 participants, including primary care clinicians, mental health clinicians, and patients with MCCs and depression or anxiety. Participants were introduced to TES prototypes that used various formats (eg, worksheets and artificial intelligence chatbots) to elicit and communicate patients' values. Prototypes were iteratively refined based on participant feedback. Data from these sessions were analyzed using reflexive thematic analysis to uncover themes related to service, technology, and implementation considerations. Three primary themes were identified. (1) Service considerations: TES should help patients translate elicited values into actionable treatment plans and include low-burden, flexible activities to accommodate fluctuations in their mental health symptoms. Both patients and clinicians indicated that TES could be valuable for improving appointment preparation and patient-provider communication through interpersonal skill-building. (2) Technology considerations: Patients expressed openness to TES prototypes that used artificial intelligence, particularly those that provided concise summaries of appointment priorities. Visual aids and simplified language were highlighted as essential features to support accessibility for neurodiverse patients. (3) Implementation considerations: Clinicians and patients favored situating values elicitation in mental health care settings over primary care and preferred self-guided TES that patients could complete independently before appointments. Findings indicate that TES can address the unique needs of patients with MCCs and mental health challenges by facilitating values-based care. Key design considerations include ensuring TES flexibility to account for fluctuating mental health symptoms, facilitating skill-building for effective communication, and creating user-friendly technology interfaces. Future research should explore how TES can be integrated into health care settings to enhance care coordination and support patient-centered treatment planning. By aligning TES design with patient and clinician preferences, there is potential to bridge gaps in care for this complex patient population.

The wing on the NASA F-111 transonic aircraft technology airplane was modified to provide flexible leading and trailing edge flaps. This wing is known as the mission adaptive wing (MAW) because aerodynamic efficiency can be maintained at all speeds. Unlike a conventional wing, the MAW has no spoilers, external flap hinges, or fairings to break the smooth contour. The leading edge flaps and three-segment trailing edge flaps are controlled by a redundant fly-by-wire control system that features a dual digital primary system architecture providing roll and symmetric commands to the MAW control surfaces. A segregated analog backup system is provided in the event of a primary system failure. This paper discusses the design, development, testing, qualification, and flight test experience of the MAW primary and backup flight control systems.

Magnetostrictive (MS) materials exhibit a large strain and a high energy-density, because of their large MS coupling coefficient. In particular, an MS actuator that uses Terfenol-D generates great-force and strain. The efficiency of an MS actuator is highly dependent on the pre-stress, magnetic field intensity, magnetic bias and thermal expansion. The specific type or shape of permanent magnet (PM) needed for a given magnetic bias is determined using numerical simulation. According to magnetic field the heat created by resistance influences the thermal expansion. This paper proposes the optimal exterior PM for achieving a magnetic bias and minimizing the ohmic heat effect with a geometric composite of an electromagnet considered to be a practically precise MS actuator.

The Population Studies Research Network of Cancer Care Ontario hosted a strategic planning workshop to establish an agenda for a prevention intervention research program in Ontario, including priority topics for investigation and design considerations. The two-day workshop included: presentations on background papers developed to facilitate participants' preparation for and discussions in the workshop; keynote presentations on intervention research concerning primary prevention of chronic diseases, design and study implementation considerations; a dedicated session on critical and creative thinking to stimulate participation and discussion topics; break out groups to identify, discuss and present study ideas, designs, implementation considerations; and a consensus process to discuss and identify recommendations for research priorities and next steps. The retreat yielded the following recommendations: 1) develop an intervention research agenda that includes working with existing large-scale cohorts; 2) develop an intervention research agenda that includes novel research designs that could target individuals or groups; and 3) develop an intervention research agenda in which studies collect data on costs, define stakeholders, and ensure clear strategies for stakeholder engagement and knowledge transfer. The Population Studies Research Network will develop options from these recommendations and release a call for proposals in 2014 for intervention research pilot projects that reflect these recommendations. Pilot projects will be evaluated based on their fit with the retreat's recommendations, and their potential to scale up to full studies and application in practice.

Magnetostrictive actuators can be profitably used to reduce vibration in structures. However, this technology has been exploited only to develop inertial actuators, while patches actuators have not been ever used in practice. Patches actuators consist on a layer of magnetostrictive material, which has to be stuck to the surface of the vibrating structure, and on a coil surrounding the layer itself. However, the presence of the winding severely limits the use of such devices. As a matter of fact, the scientific literature reports only theoretical uses of such actuators, but, in practice it does not seem they were ever used. This paper presents an innovative solution to improve the structure of the actuator patches, allowing their use in several practical applications. The principle of operation of these devices is rather simple. The actuator patch is able to generate a local deformation of the surface of the vibrating structure so as to introduce an equivalent damping that dissipates the kinetic energy associated to the vibration. This deformation is related to the behavior of the magnetostrictive material immersed in a variable magnetic field generated by the a variable current flowing in the winding. Contrary to what suggested in the theoretical literature, the designed device has the advantage of generating the variable magnetic field no longer in close proximity of the material, but in a different area, thus allowing a better coupling. The magnetic field is then conveyed through a suitable ferromagnetic structure to the magnetostrictive material. The device has been designed and simulated through FEA. Results confirm that the new configuration can easily overcome all the limits of traditional devices.

Initial studies on a novel thick-film magnetostrictive material are presented. The screen printable thick-film is based on the giant magnetostrictive material Terfenol-D. The development of the paste and of a suitable measurement system is described. Initial values for the magnetostriction of the thick-film are reported and compared with those of other composite magnetostrictive materials.